Apparatus and method for delivering ablative laser energy and determining the volume of tumor mass destroyed

ABSTRACT

An apparatus and method for determining a volume of tumor mass destroyed. The present invention includes a temperature probe and a laser probe having a temperature sensor. The laser probe and temperature probe are inserted to measure a temperature of the tumor mass and a temperature of tissue mass surrounding the tumor mass. By determining the volume of tumor mass destroyed, a graphical representation of the volume of tumor mass destroyed is provided whereby real-time visual monitoring of the destruction of the tumor mass is achieved.

PRIORITY CLAIM

This application is a continuation of and claims the benefit of priorityto U.S. patent application Ser. No. 10/754,827 filed Jan. 9, 2004, whichis incorporated herein in its entirety and which is a continuation ofand claims the benefit of priority to U.S. Pat. No. 6,701,175 issued onMar. 2, 2004, which is a continuation of and claims the benefit ofpriority to U.S. Pat. No. 6,603,988 issued on Aug. 5, 2003.

DESCRIPTION

The present invention relates in general to a method and apparatus fordelivering ablative laser energy and determining the volume of tumormass destroyed, and in particular to a method and apparatus fordetermining the volume of tumor mass destroyed by a minimally invasivetreatment, such as interstitial laser therapy, such that a graphicalrepresentation of the destroyed tumor mass can be displayed forreal-time visual monitoring of the destruction of tumor mass.

BACKGROUND OF THE INVENTION

Percutaneous in situ or on-site treatment of malignant breast tumors bylaser therapy is being developed in part due to the fact that breastcancer is being detected at earlier stages because of the increasingnumber of women receiving mammograms annually. If breast cancer andother cancers or tumors are detected in early development, the tumor canbe effectively treated using an ablative agent such as laser energy.

Image-guided laser treatments of malignant tumors such as, breast,liver, head and neck tumors, have been in development for more than adecade. For example, U.S. Pat. No. 5,169,396 (“the '396 patent”) issuedto Dowlatshahi is directed to the interstitial application of laserradiation therapy to tumor masses and is incorporated herein byreference. In general, the apparatus of the '396 patent includes a probehaving a thin metallic cannula for insertion into a tumor mass, a laserfor generating light having a chosen wavelength and intensity, and anoptical fiber for receiving and transmitting the laser light to thetumor mass, whereby the optical fiber is inserted into the cannula suchthat a chosen physiologically acceptable fluid can flow coaxiallybetween the cannula and the optical fiber. In addition, a heat sensingmember is inserted adjacent into the tumor mass for monitoring the tumortemperature. The devitalized tumor is gradually cleared by the bodyimmune system and within six months is replaced with a scar.

However, the treatment of tumors and in particular the specifictreatment of breast tumors is generally known to be more difficult dueto the fact that it is difficult to determine the three dimensionalboundaries of the tumor, and thus, difficult to determine when all ofthe tumor has been destroyed.

To address this problem, medical researchers have utilized a variety oftumor mass identification techniques for determining the size and outerboundaries of a tumor mass. Examples of conventional identificationtechniques that have been employed in combination with laser therapy aremagnetic resonance imaging, radiographic and sonographic techniques.When utilizing an identification technique, coordinates identifying theactual size of the tumor mass are determined by using stereotactictechniques or the like.

To solve this problem, at the time of laser treatment, markers may beplaced in a 0.5-1.0 cm zone of “normal” tissue to demarcate the zone inwhich the tumor extension may exist. This ring of “normal” tissue isequivalent to a cuff of tissue engulfing the tumor removed duringconventional surgery (i.e., a lumpectomy). The boundaries of the ringsurrounding the tumor are marked at 3, 6, 9 and 12 o'clock locations byinserting metal markers through a needle. The insertion points areprecisely determined by known stereotactic technique using acommercially available stereotactic table.

Such marker elements are the subject of U.S. Pat. No. 5,853,366 (“the'366 patent”) issued to Dowlatshahi is directed to a marker element forinterstitial treatment. In general, the '366 patent discloses a markerelement that can be positioned wholly within the body of a patient byutilizing a guide member having a guide path so as to mark a tumor massof interest. The marker element is made of a radiopaque material whichincludes any material that is capable of being detected by conventionalradiographic, sonographic or magnetic techniques.

Medical researchers have also employed non-surgical techniques otherthan laser therapy to treat breast tumors. For example, radio frequency,microwave, and cryogenic-related treatments have been attempted.

The present invention recognizes the above described problem, that is,to provide a non-cutting treatment for cancer and in particular forbreast cancer that can be relied upon to determine when the entire tumoris effectively destroyed. There is accordingly a need for a non-cuttingbreast cancer therapy which addresses this problem and the problemsarising from the difficulty in determining whether the tumor iscompletely destroyed.

SUMMARY OF THE INVENTION

The present invention solves the above problems by providing anapparatus and method for determining a volume of tumor mass (such asbreast cancer) destruction in tissue mass (such as breast tissue) withinthe body of a patient such that a graphical representation of thedestroyed mass can be preferably superimposed onto an image of theactual tumor mass whereby the destruction of tumor mass can be visuallymonitored in real-time. The preferred embodiment of this invention isdescribed in conjunction with breast tissue and breast cancer or tumors,although it should be appreciated that the present invention may beadapted to be implemented for other tumor or cancer treatment. Thepreferred embodiment of the present invention is also implemented with apatient positioned on a commercially available stereotactic table. Theinvention may alternatively be implemented using ultrasound and magneticresonance imaging (MRI) techniques, provided that the tissue mass suchas the breast is immobilized and the target is fixed.

The apparatus of one embodiment of the present invention preferablyincludes a laser gun. The laser gun is adapted to receive a laser probehaving a temperature sensor thereon and a temperature probe having aseries of temperature detectors thereon. The laser gun inserts the laserprobe into the tumor mass to facilitate providing an effective amount oflaser radiation and measuring the tumor temperature at the applicationpoint of the laser. The gun also subsequently inserts the temperatureprobe into the body preferably in close proximity of the tumor mass. Thetemperature probe measures the body or tissue temperature at variouslocations in proximity of the tumor mass during interstitial lasertherapy. The laser probe and temperature probe preferably includeposition marks to enable the operator to precisely position anddetermine the position of the probes relative to each other.

The apparatus preferably includes a computer control system that iselectrically connected to the laser gun and its components, namely, thelaser probe and sensor and the temperature probe and detectors. Thecomputer control system determines the volume of tumor mass destroyed byutilizing operational data, such as, the distance between thetemperature sensors, temperature data, that the control system receivesfrom the laser probe and temperature probe. The computer control systemcalculates the volume of tumor mass destroyed at any given time duringthe interstitial laser therapy based upon the tumor mass temperature andthe body or tissue mass temperature surrounding the tumor mass.

As the computer control system calculates the volume of tumor massdestroyed, the computer control system displays sequential graphicalrepresentations of the amount of destroyed tumor mass which issuperimposed onto an image of the actual tumor mass in real-time. Thisgraphic display thereby enables doctors to visually monitor the amountof tumor mass destroyed in real-time during the interstitial lasertherapy such that the user can determine when the tumor mass destructionis effectively complete.

It is therefore an advantage of the present invention to provide anapparatus and method for calculating the volume of tumor massdestruction such that a graphic representation of the destroyed tumormass can be displayed.

It is another advantage of the present invention to provide real-timevisual monitoring of the destruction of tumor mass during laser therapy.

It is a further advantage of the present invention to provide anapparatus and method for determining when the destruction of tumor massis effectively complete.

It is still further an advantage of the present invention to provide anapparatus and method for determining when the destruction of a breasttumor mass is effectively complete during interstitial laser therapy.

Other objects, features and advantages of the present invention will beapparent from the following detailed disclosure, taken in conjunctionwith the accompanying sheets of drawings, wherein like referencenumerals refer to like parts, components, processes and steps.

DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1A is a perspective view of the apparatus of the present inventionfor determining the volume of tumor mass destroyed.

FIG. 1B is a perspective view of the apparatus of the present inventionwhich illustrates the laser gun.

FIG. 2A is a schematic diagram of the laser probe and temperature probeprior to insertion into the tissue mass or body containing the tumormass.

FIG. 2B is a schematic diagram of the laser probe and temperature probeinserted into the tissue mass containing the tumor mass.

FIG. 3 is a schematic diagram of the laser probe and temperature probeillustrating the relationship of the volume of tumor mass destroyed withrespect to the temperature sensor of the laser probe and the temperaturedetectors of the temperature probe.

FIGS. 4A to 4C illustrate the graphically superimposed tumor massdestruction zone at a beginning, subsequent and final stages of lasertherapy for visual real-time monitoring of the destruction of the tumormass.

FIGS. 4D to 4H illustrate alternative graphical representations of thetumor mass destruction zone at beginning, subsequent and final stages oflaser therapy for visual real-time monitoring of the destruction of thetumor mass.

FIGS. 4I and 4J illustrate a further alternative graphical barrepresentation of the temperature at Tc, T1, T2, T3, T4 and T5 atdifferent stages of the destruction of the tumor mass.

FIGS. 5A, 5B and 5C illustrate blood flow within the tumor mass andtissue mass surrounding the tumor mass before and after treatment asmeasured by color doppler ultrasound. FIG. 5A illustrates blood flowprior to treatment without the aid of a contrasting agent. FIG. 5Billustrates blood flow prior to treatment with the aid of a contrastingagent. FIG. 5C illustrates the loss of blood flow after treatment.

FIG. 6 is a photograph that illustrates an actual tumor mass destroyedfrom laser therapy of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1A, 1B, 2A and2B, the apparatus and method for determining the volume of tumor massdestroyed is generally illustrated. The present invention provides agraphical display or representation of the volume of destroyed tumormass by determining the volume of destroyed tumor mass based on therelative temperatures of the tumor mass and temperatures of tissue masssurrounding the tumor mass as described in detail below. This displaypreferably provides doctors or other operators with real-time visualmonitoring of the destruction of tumor mass so as to determine when thedestruction of the entire tumor mass is effectively complete.

The present invention monitors the temperature within and in closeproximity to the tumor mass by utilizing a temperature sensor of thelaser probe and a separate temperature probe having a number oftemperature sensors or detectors. The temperature sensor and temperatureprobe provide temperature data for determining the volume of destroyedtumor mass, and thus, for providing the real-time graphical display ofthe destroyed tumor mass.

To calculate the destroyed tumor mass volume, the temperature probe mustbe positioned correctly relative to the temperature sensor and therelative distances therebetween must be accurately determined. Thepresent invention utilizes a number of position marks located on thetemperature probe and laser probe for positioning and for determiningthe relative positioning between the temperature detector and the laserprobe as discussed below.

In an embodiment, the present invention preferably includes a laser gun10 including a probe holder 12 employed during interstitial lasertherapy. The probe holder 12 is adapted to receive a laser probe 14 anda temperature probe 16. The laser probe 14 and temperature probe 16 areremovably inserted in and extend from the probe holder. The laser probe14 and the temperature probe 16 are held in fixed position relative toeach other by the gun. The positioning of the laser probe 14 andtemperature probe 16 may be manual or computer controlled in accordancewith the present invention.

The laser probe 14 includes a temperature sensor 15 and is adapted toreceive an optical fiber 18 connected to a laser source 20 which isconnected to a computer control system 22. The control system 22 ispreferably connected to the temperature probe 16 and a temperaturesensor 15 of the laser probe 14 via a temperature control device 24 soas to facilitate electrical connection with the computer control system22. However, the laser probe 14 and temperature probe 16 can haveseparate control systems each connected to a central computer controlsystem (not shown).

More specifically, the laser probe 14 includes a thin metallic cannulafor insertion into the tumor mass and an optical fiber for receiving andtransmitting the laser light or radiation to the tumor mass, whereby theoptical fiber is inserted into the cannula such that a chosenphysiologically acceptable fluid or anesthetic agent can flow betweenthe cannula and the optical fiber as described in the '396 patent whichis herein incorporated by reference as discussed above. In a preferredembodiment, the thin metallic cannula was approximately 18 centimetersin length and made from stainless steel ranging from 16 gauge to 18gauge, but preferably 16 gauge. In addition, the optical or laser fiberis a quartz fiber ranging from 400 nanometers (nm) to 600 nm in diameterwith a spherical tip. The optical fiber is commercially available, forexample, from SURGIMED in Woodland, Texas.

Any suitable fluid pump 26 can be utilized to deliver the fluid suchthat the central temperature of the tumor does not exceed 100° C. orfall below 60° C. during laser therapy. In an embodiment, the fluid canbe delivered at a rate ranging from 0.5 milliliters/minute (ml/min) to2.0 ml/min.

The laser source 20 generates and supplies an effective amount of laserradiation to the laser probe 14. The laser source 20 is preferably adiode laser. In particular, the laser source 20 is a semiconductor805-nanometer diode laser that is commercially available, for example,from Diomed in Cambridge, England. However, the present invention is notlimited to the use of a diode laser and can utilize a variety ofdifferent and suitable laser sources.

The laser probe 14 also includes a temperature sensor 15 as previouslydiscussed. The temperature sensor 15 is employed to effectively measurea temperature of the center of the tumor mass as the tumor mass isdestroyed. The temperature sensor 15 is preferably attached directly bysoldering or other like attachment mechanism to the laser probe 14 so asto measure the tumor mass temperature at a distal end 28 of the laserprobe 14, preferably located at a center region of the tumor mass.

The distal end 30 of the temperature probe 16 is inserted into the bodywithin the tissue mass of the body region that is in proximity of (i.e.,preferably 1.0 cm away) and surrounds the tumor mass. The temperatureprobe 16 includes a series of temperature detectors 32 or sensors thatare positioned at various distances or intervals (i.e., preferably 0.5cm) along the temperature probe. In a preferred embodiment, thetemperature probe 16 is made from stainless steel ranging from 16 gaugeto 20 gauge, preferably 16 gauge. As further illustrated in FIG. 3, thetemperature detectors 32 of the temperature probe 16 are positioned atT1, T2, T3, T4 and T5. Based on this configuration, tissue masstemperature measurements are taken at various distances away from thetumor mass surface. This temperature data is utilized in conjunctionwith the relative distances of the temperature sensors to calculate thevolume of tumor mass destroyed, and therefore is utilized to determinewhen the entire tumor mass is effectively destroyed as discussed below.

As previously discussed, the relative positioning of the temperatureprobe 16 to the laser probe 14 must be determined in order to accuratelycalculate the volume of tumor mass destroyed. As shown in FIG. 1A, thetemperature probe 16 and laser probe 14 include a number of positionmarks 34 in order to determine the relative positions of the temperatureprobe 16 and laser probe 14. The position marks 34 are preferably evenlyspaced apart along a portion of a length of the temperature probe 16 andalong a portion of the length of the laser probe 14 at a preferabledistance of 0.5 cm. However, the present invention is not limited tothis distance and can include position marks spaced apart at a varietyof different positions. The operator can use these position marks tocorrectly position the laser probe and the temperature probe relative tothe laser probe.

The present invention preferably includes the computer control system 22adapted to electronically connect to the laser gun 10 and itscomponents, namely, the temperature probe and the laser probe 14 havingthe temperature sensor 15. The computer control system 22 receives datafrom the laser probe 14 and the temperature probe 16 as the tumor massis heated and destroyed. The data is utilized to calculate the volume oftumor mass destroyed at any given point in time. This calculation isbased upon the temperature data from the temperature probe 16 andtemperature sensor 15. The computer control system 22 utilizes thedestroyed tumor volume calculations for graphically depicting the volumeof tumor mass destroyed (i.e., tumor mass destruction zone) on a display36 connected to the computer control system 22.

In one embodiment, the laser gun 10 injects the laser probe 14 andtemperature probe 16 into breast tissue 38 in order to destroy a tumormass 40 located within the breast tissue 38 of a patient 41 lying on anexamination table 42. The laser gun 10 is positioned on a stereotacticplatform or table 44 which is utilized in a conventional manner toidentify the actual location of the tumor mass 40 in the breast tissue38 prior to insertion of the temperature probe 16 and laser probe 14into the breast tissue 38. In a preferred embodiment, the stereotacticplatform or table 44 is commercially available from LORAD/Trex MedicalStereoguide DSM of Danbury, Conn. However, this identification can beperformed using conventional radiographic, sonographic, thermographic,magnetic imaging or other like identification techniques.

After the tumor mass 40 location is identified, a number of markerelements 46 are preferably inserted into the breast tissue 38 in closeproximity of the breast tumor 40. The marker elements 46 are utilizedfor marking the tumor mass 40 to be treated and to allow subsequentidentification and observation of the treated area as further describedin the '366 patent herein incorporated by reference as previouslydiscussed.

By knowing the actual location of the tumor mass, the laser gun 10 canbe configured to inject the laser probe 14 and temperature probe 16 intothe breast tissue 38 at an optimal location relative to the tumor mass40 in the breast tissue 38. The present invention utilizes a probe guide48 to facilitate the insertion of the temperature probe 16 and laserprobe 14 into the breast tissue 38. The positioning of the laser probe14, temperature probe 16 and marker elements 46 relative to thepositioning of the tumor mass 40 and tissue mass surrounding the tumormass can be visually monitored on the display 36.

As previously discussed, the present invention utilizes a laser gun 10to inject the laser probe 14 and temperature probe 16 into the tumormass and tissue mass surrounding the tumor mass. The laser gun 10 can bemade of any suitable material and be constructed in a variety ofdifferent configurations. One example of such configuration isillustrated in FIG. 1B.

The laser gun 10 is positioned on a guide mechanism 52 of thestereotactic table 44 which enables the laser gun 10 to be positionedprior to insertion of the laser probe and temperature probe. The lasergun 10 includes a housing 54 for the laser probe and temperature probeand probe holders 12 which can extend from the housing for each of thelaser probe and temperature probe. The laser gun 10 further includes analignment member 56 attached to the housing for aligning the laser gunprior to insertion. The laser gun 10 can also include an inserter member58 attached to the housing for automatically inserting the laser probeand temperature probe. The laser gun 10 is connected to a control system59 which includes a computer processing unit 60. The control system 58operates to control and monitor the temperature probe and laser probeduring laser therapy, such as controlling the laser source and fluidpump and monitoring the temperature.

The laser probe 14 is first optimally inserted into the center of thetumor mass as shown in FIG. 2B. Once the laser probe 14 is optimallyinserted into the tumor mass 40, the temperature probe 16 is optimallyinserted and positioned parallel to the laser probe 14 (i.e., preferablyapproximately 1 cm away from the laser probe) as further illustrated inFIGS. 2A and 2B. The optimal locations of the temperature probe 16 andlaser probe 14 are necessary to monitor a concentric zone of heatemitted from the tip of the laser probe during treatment. As discussedbelow, the ability to monitor the concentric heat patterns of the laserprobe is necessary to effectively measure the volume of tumor massdestroyed during treatment.

Because of the importance placed on the exact and precise positioning ofthe laser probe 14 and temperature probe 16 relative to the tumor mass40, the present invention preferably utilizes the stereotactic techniquein combination with the marker elements to monitor this positioning. Thepresent invention further utilizes a plurality of position marks 34located on each of the temperature probe 16 and laser probe 14 formonitoring the axial positioning of the laser probe 14 relative to thetemperature probe 16. As previously discussed, the position marks 34 arespaced apart at known distances, preferably 0.5 cm, along each of thetemperature probe 16 and laser probe 14. Therefore, the position marks34 are utilized to visually monitor the relative positioning of thelaser probe 14 and temperature probe 16 such that manual adjustments inaddition to computer automated adjustments can be made to the relativepositioning of the laser probe 14 and temperature probe 16.

As shown in FIG. 3, the temperature probe 16 preferably includes atemperature detector T3 that contacts an outer surface of the tumor mass40 to measure a temperature at this location. The remaining temperaturedetectors, namely, T1, T2, T4 and T5 are positioned at the distances(described above) from T3 along the temperature probe. Each temperaturedetector is also located at various radial distances from thetemperature sensor Tc (i.e., the temperature at the center of the tumormass) of the laser probe 14, namely, r1, r2, r3, r4 and r5. The radialdistance between Tc and T3 (i.e., r3) is known, that is, the axialdistance between Tc and T3, preferably 1.0 cm. By knowing the distancesbetween T3 and the other temperature detectors (i.e., T1, T2, T4 and T5)and the radial distance between T3 and Tc, the radial distance from Tcto each of T1, T2, T4 and T5 can be determined by applying thePythagorean theorem, that is, for a right angled triangle having ahypotenuse length H and side lengths A and B defining the right angle,the relationship H²=A²+B² exists.

For example, (r1)²=(T1−T3)²+(r3)²=(1.0 cm)²+(1.0 cm)²=2.0 cm² whereT1−T3=1.0 cm and r3=1.0 cm. Therefore, r1=r5=(2.0 cm²)^(1/2)=1.4 cm.Based on similar calculations, r4=r2=1.10 cm where T1−T2=0.5 cm andr3=1.0 cm. Therefore, the tissue temperature surrounding the tumorrelative to the temperature at the laser fiber tip, i.e., Tc, can bemonitored by the temperature detectors, such as T1, T2, T3, T4 and T5,at various known and corresponding radial distances from the laser fibertip, such as r1=1.4 cm, r2=1.10 cm, r3=1.0 cm, r4=1.10 cm and r5=1.4 cmas previously discussed.

By determining the radial distances, volume calculations are made ateach of the temperature detector locations preferably based upon theknown calculation for a volume of a sphere V, that is V=4/3Πr³, where ris the radial distance from the center of the sphere and Π is theuniversally accepted constant value of 22/7, that is, the value of theratio of the circumference of any circle relative to its diameter. Whenthe temperature at any one of the temperature detectors reaches a levelat which the tumor mass is destroyed, the volume calculation at each ofthe temperature detectors effectively corresponds to the volume of tumormass destroyed within the spherical region having a radial distanceassociated with the temperature detector(s), namely, r1, r2, r3, r4 andr5.

For example, when the laser radiation is first applied, the tumor mass40 is destroyed in a region at and near Tc. As time passes, the volumeof tumor mass destroyed increases in correlation to an increase in thetemperature as measured by T3. Therefore, the volume of tumor massdestroyed is effectively less than the volume corresponding to thespherical region having a radial distance of r3.

When T3 reaches or increases to a temperature, preferably 60° C., whichwould destroy the tumor mass, that is, the tumor mass destructiontemperature, the volume of tumor mass destroyed effectively correspondsto the volume of a spherical region having a radial distance of r3. Thespherical shape of the destroyed tumor mass has been documented onrodent mammary tumors and thirty-six patients with breast cancer whoselaser treated tumors were serially removed and sectioned by pathologistsand reported.

To ensure that the entire tumor mass is effectively destroyed, the lasertreatment continues until the temperatures as measured by the other orouter temperature detectors, namely, T1, T2, T4 and T5, reach orincrease to the tumor mass destruction temperature, preferably 60° C.When this occurs, the tumor mass is effectively destroyed within thevolume of the spherical region having a radial distance associated withthe outer temperature detectors, namely, r1, r2, r4 and r5. The lasertreatment ends when a temperature as measured by the outermosttemperature detector(s), such as T1 and T5, increases to the tumor massdestruction temperature, preferably 60° C.

It should be appreciated that the amount of laser energy which isnecessary to destroy the tumor mass and the tissue mass surrounding thetumor mass can also be determined. Based on previous studies conductedby the inventor, the destruction of approximately 1 cm³ of tumor massand/or tissue mass surrounding the tumor mass requires approximately2500 Joules (J) of laser energy. (See, for example, Dowlatshahi et al.,Stereotactically Guided Laser Therapy of Occult Breast Tumors, ARCH.SURG., Vol. 135, pp. 1345-1352, November 2000). By calculating theamount of tumor mass destroyed and assuming that the amount of tumormass destruction requires approximately 2500J/cm³ of laser energy, theamount of laser energy (J) which is necessary to destroy the volume oftumor mass can be calculated.

It should be appreciated that the present invention is not limited tothe number, type, positions, and locations of the temperature detectors.A variety of locations and number of detectors may be utilizeddepending, for example, on the tumor treatment conditions, such as, thetype and location of the tumor. In a preferred embodiment, thetemperature detectors are positioned to effectively monitor thedestruction of tumor mass to a radial distance from the actual tumormass associated with the outer temperature detectors (i.e., T1 and T5).

It should also be appreciated that the present invention is not limitedto the tumor mass destruction temperature. A variety of differenttemperatures may be utilized to correspond to the tumor mass destructiontemperature depending on the tumor treatment conditions as describedabove. In a preferred embodiment, the preferred tumor mass destructiontemperature is at least 60° C.

The computer control system utilizes the tumor mass destructioncalculation(s) as described above to provide a graphic display 62 orrepresentation of the destroyed tumor mass that is preferablysuperimposed onto an image of the actual tumor mass taken prior totreatment as illustrated in FIG. 4A. The graphic display 62 of thedestroyed tumor mass is preferably displayed as a circular (2-D) orspherical (3-D) symbol. The marker elements are also graphicallydisplayed in addition to the tumor mass.

In FIG. 4B, the display 62 illustrates the laser probe 14 andtemperature probe 16 after insertion into the breast tissue. The tip 64of the laser probe 14 is centrally located within the tumor mass 40, andthe temperature probe 16 is positioned relative to the laser probe 14 aspreviously discussed. As the temperature increases spatially andconcentrically away from the tip of the laser probe, the temperaturedetector at T3 measures a tumor mass destruction temperature (i.e.,preferably 60° C.). At this temperature, the destroyed tumor mass symbol66 appears as illustrated in the display of FIG. 4B. As the temperatureat T1 and T5 reach the tumor mass destruction temperature, the destroyedtumor mass symbol 67 expands to include the destroyed tumor mass regionassociated with T1 and T5 as shown in FIG. 4C.

The tumor mass destruction symbol extends outwardly from the actualimage of the tumor mass by a distance associated with the location ofthe outer temperature detectors of the temperature probe (i.e., T1 andT5). At this distance, the tumor mass destruction is effectivelycomplete as further illustrated in FIG. 4C. This distance ranges fromabout 0.25 cm to about 0.75 cm, preferably ranging from about 0.4 cm toabout 0.5 cm. The graphic display of the present invention provides areal-time visual monitoring of the destruction of tumor mass in contrastto known displays that only illustrate the temperature at variouslocations of the tumor mass by a conventional bar graph.

An alternative embodiment of the graphical representations of the tumormass destruction zone at the beginning, subsequent and final stages oflaser therapy for visual real-time monitoring of the destruction of thetumor mass is illustrated in FIGS. 4D, 4E, 4F, 4G and 4H. FIG. 4Dillustrates the tumor without any destruction zone. FIGS. 4E, 4F, 4G and4H illustrates the destruction zone increasing in size to expand beyondthe tumor zone. It should be appreciated that different cross hatching,shading and graphical images can be used to graphically illustrate thetumor mass and the destruction zone. It should also be appreciated thatdifferent colors can be graphically used to illustrate the tumor massand the destruction zone.

It should further be appreciated that a further graphical representationof the temperatures could be implemented in conjunction with the abovementioned graphical images. FIGS. 41 and 4J illustrate a bar graph whichis preferably also provided to the operator of the system. The bargraphs show the temperature at Tc, T1, T2, T3, T4 and T5 at differentpoints in time. As illustrated in FIG. 41, the temperature at Tc is muchgreater than the temperature at T3, which is greater than thetemperature at T2 and T4, which is greater than the temperature at T1and T5. As the tumor mass destruction temperature increases at thesepoints and the destruction zone increases, the bar graph changes to apoint in time as illustrated in FIG. 4J. At this point, the areas at T1and T5 are above the tumor mass destruction temperature which ispreferably 60° C. Therefore, the operator knows that the mass has beendestroyed in addition to the graphical representations described above.

In an alternative embodiment, the present invention utilizes a bloodcirculation test in combination with real-time visual monitoring todetermine when the destruction of the entire tumor mass is effectivelycomplete. Any suitable blood circulation test can be utilized. However,contrast-enhanced color doppler ultrasound is the preferred techniquethat utilizes a suitable contrasting agent and a suitable transducerultrasound for observing blood with color as it circulates in the tumormass and tissue mass (i.e., breast tissue) surrounding the tumor mass.The blood circulation test is conducted before and after treatment andthe results are compared to determine whether the tumor mass waseffectively destroyed.

Any suitable transducer and contrasting agent may be utilized. In apreferred embodiment, the transducer ultrasound is a 7.5 MHz lineararray transducer ultrasound that is commercially available from ATL inBothel, Wash.

In addition, the contrasting agent is preferably a sonicatedalbumin-based agent, that is, an albumin-based material havinggas-injected bubbles. It should be appreciated that the reflection ofsound waves from the bubbles within the albumin-based material producesa color response indicative of blood flow or circulation. In particular,the contrasting agent is OPTISON which is a commercially availableproduct from Mallinkrodt of St. Louis, Mo.

Before treatment, an effective amount of the contrasting agent ispreferably injected into a vein. The contrasting agent is utilized toenhance the image of blood circulation that results from the colordoppler ultrasound technique. The effectiveness of the contrasting agentis shown by comparing the color doppler ultrasound blood flow images ofFIGS. 5A and 5B. The contrasting agent was utilized to produce the bloodflow image of FIG. 5B and not FIG. 5A. By comparing these figures, it isevident that the blood flow image of FIG. 5B is more enhanced than theblood flow image of FIG. 5A.

Turning to FIG. 5B, the contrast-enhanced color doppler ultrasoundmeasured a substantial amount of blood flow within the tumor mass andtissue mass surrounding the tumor mass. After treatment, the contrastingagent is again injected to observe blood flow in and around the tumormass. As further predicted, there was effectively no blood flow withinthe tumor mass and surrounding area as measured by the above-describedultrasound technique as shown in FIG. 5C. This indicates that the tumormass and tissue mass surrounding the tumor mass was effectivelydestroyed. If the tumor mass and the surrounding tissue mass has beendestroyed, blood circulation in this treated region effectively cannotbe observed by color doppler ultrasound. A comparative analysis betweenthe results of the blood circulation test before and after treatment isutilized to make the determination as to whether the entire tumor massis destroyed.

This change in blood circulation in and around the tumor mass can alsobe observed by injecting an effective amount of the contrasting agentinto the vein during laser therapy. This provides real-time monitoringof the blood circulation within the tumor mass and tissue masssurrounding the tumor mass during laser treatment. As more and more ofthe tumor mass and surrounding tissue mass is destroyed, less bloodcirculates through this region. As the blood circulation decreases, theblood circulation test, such as the color doppler ultrasound, can beutilized to effectively measure a decrease in blood circulation aspreviously discussed. A graphical representation of the results of thecolor doppler ultrasound can be continuously monitored during lasertherapy. The graphical representation can be displayed on a separatedisplay or can be superimposed onto the actual image of the tumor massduring laser therapy. The graphical representation provides furtherreal-time monitoring of tumor destruction before the patient is removedfrom the table. Additional laser treatment can be delivered if a portionof the targeted tissue exhibits blood flow suggesting viability. Itshould be appreciated that the graphical representation can beconfigured in any suitable way such that the blood flow circulation canbe monitored.

An actual tumor mass that has been destroyed during laser therapy of thepresent invention is illustrated in FIG. 6. The void region representsthe region where the tumor mass and surrounding tissue mass weredestroyed by laser therapy. As shown in FIG. 6, the void region iseffectively circular in shape and has an approximate diameter of 2.5 to3.0 cm. FIG. 6 illustrates a cut section of a laser treated breasttumor. The red ring is the inflammatory zone and the tissue within it isdestroyed. The diameter of this ring corresponds to the diameter of theavascular zone seen by color Doppler ultrasound in FIG. 5C.

The present invention also provides a method for determining the volumeof tumor mass destroyed. The method preferably includes the step ofproviding a laser gun. The laser gun further includes a laser probe andtemperature probe as detailed above. The laser probe and temperatureprobe are inserted into the body of the patient such that the laserprobe is inserted into the tumor mass and the temperature probe isinserted into the tissue mass in proximity to the tumor mass. Aneffective amount of laser radiation is generated and directed into thetumor mass through the laser probe. The temperature sensor of the laserprobe measures the tumor mass temperature within the tumor mass. Thetemperature probe measures the tissue temperature of tissue masssurrounding the tumor mass at various positions along the temperatureprobe. The computer control system is preferably electronicallyconnected to the laser gun and its components, namely the laser probe,the temperature sensor of the laser probe, and the temperature probe,and a fluid pump. The computer control system receives temperature andlaser data from the temperature and laser probes for determining orcalculating a volume of tumor mass destruction as detailed above. Thecomputer (or operator) adjusts the fluid flow delivered by the fluidpump so that the central temperature of the tumor, i.e., Tc, does notexceed 100° C. or fall below 60° C. during laser therapy.

The computer control system utilizes this calculation to create adisplay that graphically superimposes the destroyed tumor mass onto theimage of the actual tumor mass. By graphically showing the amount oftumor mass destroyed, the doctor can visually monitor the destruction oftumor mass under real-time so as to determine when the destruction oftumor mass is effectively complete as detailed above.

In an alternative embodiment, the method of the present inventionincludes the step of identifying the tumor mass prior to insertion ofthe laser gun into the tumor mass. The identification step is performedusing conventional radiographic, sonographic or magnetic imagingtechniques. Preferably, coordinates identifying the actual location ofthe tumor mass are determined using stereotactic techniques or the likeas previously discussed.

In another alternative embodiment, the present invention utilizes ablood circulation test, such as color doppler ultrasound, before andafter treatment to provide further evidence when the entire tumor massis effectively destroyed as previously discussed. The blood circulationtest can also be utilized during laser therapy to provide furtherreal-time monitoring of the tumor mass destruction as further discussedabove.

It should be appreciated that the present invention is not limited tointerstitial laser therapy, and particularly, interstitial laser therapyfor the destruction of a breast tumor. The present invention may applyto a variety of different non-surgical treatments for the destruction ofa variety of different tumor masses.

It should be understood that modifications and variations may beeffected without departing from the scope of the novel concepts of thepresent invention, and it should be understood that this application isto be limited only by the scope of the appended claims.

1. An apparatus displaying a volume of a tumor mass destroyed, theapparatus comprising: means for measuring a temperature of at least partof the tumor mass; and means for providing a graphical representation ofthe volume of the tumor mass destroyed based at least in part upon saidtemperature measurement.
 2. The apparatus of claim 1, which includesmeans for determining a temperature at a point in proximity of the tumormass.
 3. The apparatus of claim 1, wherein the graphical representationof the volume of the tumor mass destroyed is superimposed onto an imageof the tumor mass to provide real-time visual monitoring of thedestroyed tumor mass.
 4. The apparatus of claim 3, wherein the graphicalrepresentation includes a geometrical symbol.
 5. The apparatus of claim3, wherein the real-time visual monitoring of the destroyed tumor massis provided during interstitial laser therapy.
 6. The apparatus of claim1, which includes means for conducting a blood circulation testemploying a contrasting agent to determine the volume of the tumor massdestroyed.
 7. The apparatus of claim 6, wherein the blood circulationtest includes a contrast-enhanced color doppler ultrasound test.
 8. Theapparatus of claim 7, wherein the blood circulation test confirms thatan entire amount of the tumor mass is effectively destroyed.
 9. Theapparatus of claim 8, wherein the blood circulation test is conductedbefore and after the tumor mass is destroyed.
 10. An apparatusdisplaying a volume of a tumor mass destroyed, the apparatus comprising:means for measuring at least a temperature at one point in proximity ofthe tumor mass; and means for providing a graphical representation ofthe volume of the tumor mass destroyed based at least in part upon thetemperature measurement.
 11. The apparatus of claim 10, wherein thegraphical representation of the volume of the tumor mass destroyed issuperimposed onto an image of the tumor mass to provide real-time visualmonitoring of the destroyed tumor mass.
 12. The apparatus of claim 11,wherein the graphical representation includes a geometrical symbol. 13.The apparatus of claim 11, wherein the real-time visual monitoring ofthe destroyed tumor mass is provided during interstitial laser therapy.14. The apparatus of claim 10, which includes means for conducting ablood circulation test that employs a contrasting agent to determine thevolume of the tumor mass destroyed by the amount of laser energy. 15.The apparatus of claim 14, wherein the blood circulation test includes acontrast-enhanced color doppler ultrasound test.
 16. The apparatus ofclaim 15, wherein the blood circulation test confirms that an entireamount of the tumor mass is effectively destroyed.
 17. The apparatus ofclaim 16, wherein the blood circulation test is conducted before andafter the tumor mass is destroyed.
 18. An apparatus for determining avolume of tumor mass destroyed, the apparatus comprising: a laser probehaving a temperature sensor operable to measure a temperature of saidtumor mass; a computer control system electrically connected to thelaser probe and operable to determine the volume of tumor mass destroyedbased upon the tumor mass temperature and the tissue temperature; adisplay connected to the computer control system and operable to displaya graphical representation of the volume of tumor mass destroyed; andmeans for conducting a blood circulation test employing a contrastingagent to determine the volume of the tumor mass destroyed by the amountof the laser energy.